first

first combinator takes two or more parsers and applies them in order. Returns the value of the first parser.

Usage

const Parser = first(
  whole(),
  whitespace(),
  string('spartans')
)

Success

run(Parser).with('42 spartans')

{
  isOk: true,
  start: 0,
  end: 11,
  pos: 11,
  value: 42
}

Failure

run(Parser).with('42 haskellers')

{
  isOk: false,
  start: 3,
  end: 11,
  pos: 3,
  expected: 'spartans'
}